Refrigerating apparatus



May 25, 1943. D. L. KAUFMAN y i REFRIGERATING APPARATUS Fild oct. 28,1940 1Nv NTOR. y

ATT NEYs Patented May 25, 1943 REFRIGERATIN G APPARATUS Daniel L.Kaufman, Dayton,

Ohio, assignor to General Motors Corporation, Dayton, Ohio, a

corporation of Delaware Application October 28, 1940, Serial No. 363,072

Claims.

This invention relates to refrigerating apparatus and moreparticularlyto evaporator control means.

Ordinarily, expansion valves are controlled by pressure of therefrigerant in the evaporator and the temperatureadjacent the outlet ofthe evaporator. Such a valvetends to maintain the evaporator filled withrefrigerant at a substantially constant temperature. This issatisfactory as long as the environment temperature remains constant andthe evaporator operates above freezing temperatures. When the evapo-Arator operates below freezing temperatures it is desirable to defrostthe evaporator periodically in order to remove the which acts asinsulation upon the evaporator and reduces the rate of heat transfer.Various schemes have been proposed from time for doing this.

It is an object of my invention to provide upon an ordinary expansionvalve in the refrigerating system an additional snap acting controlwhich will be operated periodically to positively close the valve for aperiod sumcient to defrost the evaporator after which the expansionvalve and the refrigerating system is returned automatically to normaloperation.

It is another object of my invention to provide an ordinary expansionvalve with asnap acting control which is controlled by evaporatortemperature and/or the temperature of the air or medium cooled by theevaporator.

It is another object of my invention to provide an expansion valve vwithan improved simplified form lof pressure or-temperature operated snapacting control.

In installations Where frosting of the evaporating means is not aproblem, it is sometimes desirable to cylically control the flow ofrefrigerant to each evaporating means individually according ,to thetemperature of the medium cooled thereby.

It is, therefore, another object of my invention to close the expansionvalve of anevaporating means when the temperature of the medium cooledthereby reaches a predetermined low limit and to open the expansionvalve when the temperature of the medium reaches a predetermined higherlimit.

, Further objects and advantages ofthe present invention will beapparent from the following description, referenceV being had to theaccompanying drawing, wherein a preferred form of the present inventionis clearly shown. In the drawing:

Fig. 1 is a diagrammatic illustration of a refrigerating system togetherwith an expansion valve, in section, disclosing one form of myinvention; 'and coating offrost Fig. 2 is a fragmentary view showing adetail of the expansion valve.

Briefly, I have shown an expansion valve having a valve needle retainedin place by a spring means. This valve is provided with a snap actingcontrol, operated through a pressure system which is thermostaticallycontrolled by evaporator temperature and the temperature of the mediumcooled. Thus, when the temperature of the thermostatic control islowered sufficiently, the snap acting mechanism is operated topositively close the valve until the evaporator defrosts. The rise intemperature of the evaporating means above defrosting temperatureoperates a snap acting means to remove from valve closing position inorder to allow the valve to open and operate normally.

Referring now to the drawing, there is shown a motor-compressor unitincluding an electric motor 20 for driving a compressor 22 whichwithdraws refrigerant from the evaporating means 24 through the suctionconduit 2S and discharges the compressed refrigerant into the condenser28. The compressed refrigerant is liquefied in the condenser 28 andcollected in the receiver 30. From the receiver 3D, the liquid issupplied through the liquid supply conduit 32 to' an expansion valve 34which controls the flow of liquid refrigerant into the evaporating means213. The electric motor 2D, which drives the compressor 22, may becontrolled manually or by low pressure or thermostatic control. Whileonly a single evaporating means is shown connected to thecompressor, theinvention may also be applied toy multiple systems wherein itsadvantages are increased and are even more irnportant.

The expansion valve A33 and the evaporating meansf24 are located withinaninsulated compartment 36 so that the evaporating means 23 may cool theair therein so as to keep the compartment at a desirable refrigeratingtemperature. The liquid refrigerant, which is supplied to the expansionvalve 34 through the liquid supply conduit 32, enters the valve by aconnection 38 which is connected by a passage 40 extending diagonallyupwardly to the central axis of the valve where it connects to a. down'-wardly extending passage which receives the threaded valve seat bushing42. This valve seat bushing 42 opens into a cylindrical chamber 4Sprovided in the body of the valve.

'I'he upperl portionof this cylindrical chamber 4l connects to an outletpassage 46 provided with a connection 4,8 to the evaporator means 24.This passage 46 is connected by a small vertical passage 50extendingwithin theinterior of a metal bellows member 52 provided in thehead of the valve. The end plate of this bellows 52 is connected bythree symmetrically positioned vertical pins 54 with a valve guidemember 58 which is slidable vertically. within the lcylindrical .chamber44. The valve guide member 58 carries a valve needle v58 which'isadapted to enter into and close the passage provided in the valve seatbustling 42 lto 'close the valve. The valve needle 58 is provided withan integral tapered 'collar `80 which is normally held against a'comple.

mentary seat provided in the valve guide 55 by a very light spring 82.At the bottom of the valve needle 58 there is provided an extension 64in form of an operating pin.

The bottom of the valve guide '8 is provided with a spring retainer 86whichreceives the upper end of a compression type coil spring 68 forapplying a closing pressure upon the valve needle 58. The lower end ofthi'scoil spring 58 is supported by a spring retainer 10, threaded uponan adjusting screw 12 which in turn is rotatably mounted in a bushing14, threaded into the cylindrical chamber 44 of the valve body. Theshank ofl theiadjusting screw 12 is sealed by an adjustable packinggland 15. The ad- `perature -of the l ing the heat transfer and vtheeliiciency of .the evaporator 24. This causes .a reduction intemevaporator 2| by reason of the reduced rate of the 'temperature ofthe air inthe immediate .vicinity f of the evaporator 24 but increasesthe justing screw 12 is'provided with a square head 18 for adjustment. Acap nut 80 encloses the head of the adjusting screw 10.

Thevbellows 52 at Vthe head end is enclosed by a cup-shaped sheet metalmember 82 which, like -thelower periphery ofthe bellows 52, is'sealed toa nange. 84 providedJon. the head of the valve. This provides a chamber'bf the valve 86 between the bellows and the cup-shaped member 82. l Thechamber 88 is connected by a -tube 88 with the thermostat bulb 90 whichis pro- `vided adjacent. the outlet of the evaporatmg means 24. Thisbulb, mountedin this way, is preferably charged with .a suitable gradeof activated charcoal or some other suitable absorbing 4material. The.chamber 86,J the tube Vlili and the bulb 90 are also preferably chargedat a suitable pressure with carbondioxideor some vother suitable gasnon-condensible at operating temperatures above pressure at which itoperates. Under this arrangement the pressure -within the vchamber 86 isVaried according to the temperature of the thermostatic bulb 90 byabsorption and evolution of the carbon dioxide into and out of theactivated charcoalin the bulb 90. This pressure tends to keep the valveopen sufficiently to allow the liquid .refrigerant to approach the pointat which the thermostatic bulb 90 is located. -This point,however,may beadjusted .by the adjusting-screw 18. This aol-- iustment, however, willalsochange the evaporating temperature and pressure within theevaporator 24. The bellows 52 is also responsive to the pressure withinevaporator 24 through the passage which'connects with the chamber 40within the bellows 52. l v

With such an arrangement, 'after thevalve is adjusted, the evaporator iskept substantially filled with liquid refrigerant so that the liquidrefrigerant approaches. the thermostat bulb 90. The refrigerant willalso evaporate at a substantially constant pressure within theevaporator means 24 by reason of the pressure control in the expansionvalve. In order to keep the air in thecompartment 35- suflciently coldwith the smallest-possible size of evaporator it is desirable tooperate' theevaporator normally below freezing temperatures and toadjust the-expansion valve and tocontrol the operation oflthe electricmotor accordingly. This entails a deposit of frost upon the evaporatormeans 24, which in turn 4acts as insulation, thereby reductemperature inthe-remaining portions of fthe compartment 35'.

In orderjto periodically melt the frost off the evaporator 24 plied anadditional control to the expansion' valve. In so doing I have provideda diaphragm lchamber |0| at the side of the expansion -valve whichcontains the diaphragm |03 which is clamped at itsedges to the flange|05 surrounding the diaphragm chamber |0| by a flange provided on thehousing |01. Thishousing |01'is .clamped 'to the valve body of the valve34 byscrews or some'cther means, not shown. Clamped to 'op' posite sidesof .this exible metal' diaphragm |0| are lever arms |09 and forming'asimple lever which employs the diaphragm for its pivot point. The arm|09 extends intothe cylinder .445 beneath 'the operating the valveneedle 58. A cavity is provided in the valve-guide 56 for receiving thearm |08. The

other end of the lever, namely the armv surrounds-a thimble H3. This endofthe arm is vprovided with 'a notch which receives a toggle pin ||5provided within a 'spring retaining cup ||1 which is mountedwithin thelever ||9 pivoted upon the pin |2| fixed to the housing |01 'at asuitablepoint. A compression type coil spring |23 bears against thelever ||3` and surrounds the cup-shaped spring retainer ||1.

The other end of this compression type coil spring |23 is supported by aspring retainer 4|25 which is supported by the inner end of an-adjusting screw |21 extending through the housing |01 and provided withan external'lock-nut |29.

In order to operate the snap acting mechanism', .the -thimble ||3 isprovided with upper and lower anges which engage the mounted projections|3| provided on the arm Within the thimble ||3 there is provided acompression type coil spring |33 having its lower end resting upon thelower flange. o f the thimble 3 and having its upper end supported by anadjusting screw |35 threaded into a bushing |31 provided in the housing|01. The threaded passage isclosed by the cap screw |39. The lower edofthe thimble ||3 is held by the spring |33 against the closed end ofthe lziellovvs |4| which hasits open end sealed to a .ange |43 providedon -the housingv |01. .Also fastened to this flange |43 is a cup-shapedmember |45 which sur-- rounds the bellows |4I. This provides anoperating chamber |41 between the bellowsv |44| and the cup-shapedmember |45.

This operating chamber |41 .is connected by tubing |49 with thethermostat bulb |5| which is preferably mounted upon the portion of the'evaporating means 24 where the frost disappears last upon defrosting.Frequently, this is in the central portion of the evaporating means. Thetubing |49 also connects to a second bulb |53 located adjacent theevaporating means 24. Thesebulbs'll and |53 preferably contain eitherthe same or different grades of activated charcoal.' The bulbsconnecting .tubing and operat-v ring chamber |41 preferably are chargedwith carbondidxide or some other suitable-gas at a pressure suflicientlylow to prevent condensation at any point. By this system, pressurewithin the heat transferand also reduces in a simple manner I have ap-4pin projection 84 of operating chamber |41 is controlled in accordancewith the temperatures of the two bulbs. If desired, either of thesebulbs may be omitted and the control accomplished by a single bulb.

The tension of the coil spring |33 is so adjusted that when theevaporating means 24 as a 'f result of the accumulation of frost thereonlowers its temperature, the temperature of the bulbs and |53 willbe.lowered suiliciently to allow ,the spring |33 to move the thimble H3and the bellows |4| 'downwardly to carry the lever |09 and and itstoggle pin |I5 across dead-center position so that the arm |09 engagesthe operating projection 5.4 and the valve needle to move the valveneedle 58 to closed position .regardless of the position of the valveguide 56 and its operating bellows 52. This movement normally [will movethe collar 60 away from its seat, thereby compressing the spring 62.This will stop the supply of refrigerant tothe evaporating means 24allowing it to warm up 'and causing the frost to be melted therefrom.

The toggle spring |23 is so adjusted that when the thermostat bulbs |5|and |53 reach a temperature indicating that the frost has completelycycle for intermittently removing the frost fromthe evaporating means.It ls obvlousjthat in multiple systems a snap acting expansion valvelike this may be applied to e'ach evaporator in.

the system which operates at freezing temperatures. Thus by this smalladditional control applied to the expansion valve, defrosting islndividually accomplished intermittently for each frigerant in theevaporating means and to the temperature at the outlet of theevaporating means for normally controlling the valve opening, saidexpansion valve including an independent additional snap acting controlfor closing the valve with a snap action independent of said normalcontrol means, said additional control including a Ysecond thermostaticmeans responsive to the temperature of themedium and a thirdthermostatic means responsive to the temperature of the evaporatingmeans.

2. Refrigerating apparatus including a medi'- um to be cooled, anevaporating means for cooling the medium, an expansion valve forcontrolling-the flow of refrigerant into the evaporating means, saidexpansion valve including normal control means-effectively responsive tothe pressure of the refrigerant in the'evaporatingV means and to thetemperature at the outlet of the evaporating means for normallycontrolling the valve controlV means', and a direct means for directlyapplying the force of the snap'action control upon the valve for holdingthe valve in closed position.

3. Refrigerating apparatus including a medium to be cooled-anevaporating means for cooling' the medium, an expansion valve forcontrolling the ilow of refrigerant into the evaporating means, saidexpansion valve including means effectively responsive to thepressure ofthe re-.

frigerant in the evaporating means and to thetemperature of therefrigerant adjacent the outlet 4portion of. the evaporatlngmeans fornorof the evaporating means.

v-evaporator according to the rate at which it collects frost. y

While I have illustrated my improved-control operating upon a defrostingcycle, it may also be Vused to operate upon a cycle responsive to themedium cooled or to evaporator temperature.

Where the evaporating means is used i'orl cooling water, the control maycycle according tewater temperature. In such a case. both bulbs [5| and|53 may be used, providing a control according to water andevaporatortemperature,V or the,

bulb lilvmay be omitted, providing a control according to watertemperature alone.y The evaporating means may be used forcooling air atnonfrosting temperatures or for other mediums providing a controlaccording to the Itemperature lof the medium and/or evaporatortemperature.

While the form of embodiment ofthe invention as herein disclosed,constitutes .a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope 'of' ing the medium, Aanexpansion valve for oontrolling thetlow of refrigerant into evapoiraungineens, said expansion valve-including thermostatic and pressure normalcontrol'nieans elective'ly to the ofthe rea. 'inedi- :luid motor.

4. Refrigerating apparatus including a medium to 1be'cooled, anevaporating means -for cooling the medium, an expansion valve forcontrolling the flow o f refrigerant into the evaporating means,-saldexpansion valve including means effectively responsive to thepressure of the refrigerant in the evaporating means a'nd'to thetemperature of the'refrigerant adjacent the outlet portion of theevaporating means for normally controlling the valve opening, and anadditional control for overcoming the normal control of the.

valve opening to positively close Asaid expansion valve, said additionalcontrol including means responsive to the temperature of the medium, and

means responsive to the temperature of the evaporating means;

5. Refrigerating apparatus Iincluding a medium to be cooled, anevaporating means for cooling the medium, a valve needle for controllingthe iiow of refrigerant into the evaporating means, a iluidmotorresponsive to the pressure of the refrigerant in the evaporating'meansfor controlling the opening of the valve needle, and 'a snap-actingcontrol acting independently-of said fluid motor directly upon saidvalve needle for holding the valve 'needle in closed position. saldvalve needle having a lost motion connection withsaid fluid motorallowing the valve needleto be held closed bytsaid snap-acting'meansinan d position of the dependently of the action DANIEL L, KAUFMAN.

